The German political scientist and philosopher, Samuel von Pufendorf, described the Holy Roman Empire in 1667 as a ‘monstrosity’, because it did not fit any of the recognized definitions of a state. The issue of the Empire's statehood has been the most important consideration in its historiography in recent decades: was it a state? If so, what kind? This review addresses these questions by examining how the debate on the Empire is related to wider controversies surrounding German history, the contemporary process of European integration, and about political organization in general. It explains how these debates are rooted in the political and religious disputes of the sixteenth and seventeenth centuries that still influence how the history of the Empire is written today. The four principal modern interpretations are identified and assessed: the Empire as a ‘failed nation state’, as a federation, and, more recently, as an ‘Empire-State’ or a ‘Central Europe of the Regions’. The piece concludes by offering a new explanatory framework to assess the Empire's political development.